Field of the Invention
The invention relates generally to load elevators for use in loading and unloading objects; in particular, it relates to a floor-mounted load elevator with retractable forks that render it accessible to pallet jacks.
Description of the Prior Art
In the process of handling objects, such as packages in a warehouse or a factory floor, the objects are commonly transferred manually from a pallet resting on the floor or other support to a table, a shelf, a conveyor, etc., or vice versa. Therefore, easy and ergonomic access to the objects on the pallet by a worker standing on the side of the pallet is a crucial component of the work environment in the warehouse. To that end, pallets are ordinarily placed on a load elevator of some kind so they can be lifted to render the load more accessible at the most ergonomic height possible for the workers transferring the load.
Pallets are the mainstay of shipping commerce and pallet trucks (also called pallet jacks) are the preferred method for moving palletized products on a factory floor or in a warehouse. They are relatively inexpensive and safe. Forklifts, on the other hand, are expensive and relatively dangerous; therefore, they are subject to safety regulations that require periodic training of operators and ongoing compliance with safe-practice measures, all of which increase the costs of forklift operation. For that reason many factories and warehouses limit forklift access to designated areas and only with designated certified drivers, and they forbid the use of forklifts in other areas of their premises. As a result, products like pallet trucks are the only means for transporting palletized loads to these other areas. Another disadvantage of forklifts compared to pallet jacks is the fact that they require more space to operate. Therefore, there is a need for an ergonomic lift that can be loaded or unloaded with a pallet jack rather than a forklift.
The load-elevator products devised so far in the industry have addressed these problems by adding ramps to the elevator platform in order to enable a conventional pallet jack to roll the pallet onto an elevator platform, where it is then lifted in some manner. For example, the product marketed by Bishamon Industries as the EZ Off Lifter® has an access ramp about 3 feet long that is used to roll a pallet jack about 1.75 inches higher onto the lift's fork carriage. The EZ Off Lifter® is over 8 feet long and the typical pallet truck occupies another 5 feet of space. In addition, the operator needs maneuvering room to accelerate the truck while pushing the load up the ramp or decelerate the truck when coming down the ramp with a loaded pallet. Thus, in practice, about 16 feet of floor space is required to safely maneuver a loaded pallet truck onto or off the EZ Off Lifter® and the operation of loading or unloading a heavy pallet with a pallet truck requires a substantial physical effort on the part of the operator.
Other products designed for access by pallet trucks have similar problems. For example, so-called pan lifts are lower and require a smaller ramp for access by a pallet truck, but the center of the pallet is virtually inaccessible when placed on the platform because a worker has to reach over the scissor-lift mechanism on each side of the platform. This structure is typically one foot or so wider than the pallet and the worker must reach across this additional distance to access the center of the pallet (a total of about 34″, which is much more than the length of the average person's arm). In addition, the typical pan lift is about 62″-67″ wide and about 60″ long, a large piece of equipment to walk around while reaching for objects on the pallet. Due to the sides of the pan structure that encase the pallet, the operator must move the pallet completely outside the structure before being able to maneuver and turn the pallet truck. This requires at least 12-13 feet of floor space.
Another common problem with ramped structures lies with the fact that no ramp, however well designed, works well with all pallet trucks. Pallet truck designs vary greatly and have varying amount of underclearance. Therefore, sometime the pallet truck has insufficient clearance to go up the ramp. In addition, because at some point in the operation the drive wheels of the truck are necessarily still on the floor when its fork tips are elevated over the ramp, the resulting incline causes the fork tips to drag on the underside of the pallet's upper boards and push the pallet forward, which is very undesirable.
Yet other types of lifts (so-called E-Lifts and U-Lifts, for example) are available that do not require a ramp for access, but they are mainly for use with pallets that do not have a bottom board (so-called skids). These lifts also have external hydraulic power units with hoses and electrical lines that sit along the sides or at the end of the lift, all of which represents a hazardous obstacle for the operator.
The present invention is directed at solving these problems by providing a load elevator that is accessible by a pallet truck carrying either a pallet or a skid without the use of a ramp. The elevator has a reduced footprint for use in smaller work areas and has no structure on three sides of its extended forks, so as to enable access by the pallet truck from the front or either side of the elevator. As a result, once the pallet is in place, the operator can reach over it without any obstruction.